We talk a lot about the discrimination women face in science and engineering, but a new study says there may be a bigger reason why women don't rise higher in these fields: motherhood. Right now, science and engineering departments don't know how to deal with profs, postdocs, and grad students who might also want to be moms. But there are some simple changes they could make that would help a lot.

In a study published in the March-April issue of American Scientist, Wendy Williams and Stephen Ceci write, "It is when academic scientists choose to be mothers that their real problems start. Women deal with all the other challenges of being academic scientists as well as men do. Childless women are paid, promoted and rewarded equivalently to their male peers (and in some analyses at even higher rates). Children completely change the landscape for women — but do not appear to have the same effect on the careers of men." Why does this happen? Basically, prospective scientists finish grad school and postdocs and can apply for tenure-track jobs at an average age of 33. That means they won't get tenure until they're 35 or older. Until then, they have to work their asses off doing research and publishing papers. Which isn't so compatible with being a mom. Williams and Ceci write,

Whether measured in hours spent or in percentage of one's life energy devoted, the job demands devotion to the task at a level that is extraordinarily challenging for women who are mothers of young children. The tenure system was created at a time when few women worked outside the home and when raising children was assumed to be women's work, and thus it was designed for people without significant responsibilities in household work or child care. In fact, many early professors were unmarried men who were expected to live in residence at their universities. A lot has changed since then, but the tenure system itself has remained much the same.

Result: women tend to drop out of science careers, especially in more math-intensive fields that require more research hours, when they have kids. The reality is, as they study authors point out, women are way less likely than men to have a stay-at-home or part-time-working partner to help pick up the childcare slack. New moms leave postdoctoral positions twice as frequently as new dads do, and earlier research shows that even planning to have kids in the future makes women more likely to drop out of science. Just anecdotally, I've heard young female scientists say they've given up on the idea of kids because of the demands of their career, or that they're very afraid about balancing the two.

Luckily, there are solutions. One is stopping the tenure clock — when young professors get tenure-track positions, they get a certain amount of time to prove themselves worthy of tenure through research and publishing. If they don't, they're out. But many universities will now put that clock on hold for new moms (or dads) allowing them take it slow for a year before they need to start publishing again. Still, this isn't a perfect fix. I talked to one science grad student who told me that even if your particular institution recognizes the clock-stopping, the field won't — they still might think of you as less impressive than someone who's been publishing continuously. For clock-stopping to really help, everyone would have to recognize that it's necessary and legitimate. According to the Chronicle of Higher Education, everyone who evaluates potential professors — not just their home departments — needs to understand "how stopping the clock is supposed to work, so that professors can use the benefit without fear."

The grad student also told me that balancing motherhood and science is really a "time management issue," and departments can help by easing the burdens of childcare. One way to do this is to provide onsite, affordable childcare. Lactation rooms are also important, the student said — they may seem like a small addition, but they can go a long way toward creating an institutional culture that's accepting of motherhood.

Williams and Ceci offer a few other ideas, ranging from "the use of part-time tenure-track positions for women having children that segue to full-time once children are older" to "leveraging technology to enable parents to work from home while children are young or ill." The bottom line is that if universities want to give female scientists equal opportunities — if they want to take advantage of all the available talent rather than just half of it — they need to recognize that raising kids takes time. And they need to figure out a way to give scientists that time while still letting them keep their jobs. It shouldn't be that difficult — way simpler, really, than doing science.